Hard-To-Reach Corners

Q. I’m the production supervisor for a company that makes steel office furniture. We’re proud of our paint job and the appearance of our painted products. Recently, however, we sold some furniture to a jobber in the Southwest, where the humidity is high, and have received complaints about rusting of the inside surfaces of drawers and cabinets. After some investigation of this problem, we noticed that we often do not get paint on all the internal surfaces of cabinets and drawers and we overspray on the inside compartments of steel drawers where we don’t want it. Our problem is mostly on internal structures and behind internal supports. How can we get paint onto the difficult and inaccessible areas of cabinets while eliminating overspray on the interior compartments of drawers and cabinets? S. L.

A. Paint can be applied on otherwise inaccessible areas by using the electrostatic spray application method. This method will generally cause paint to be deposited behind internal supports. The exception to this rule is the inability to paint inside corners because of the well known “Faraday Cage” effect. To overcome this effect, inside corners can be sprayed using conventional spray. The best way to eliminate overspray on inside surfaces and other unwanted areas is to mask them before painting other areas.

The most efficient way to paint internal and external surfaces of complex shaped objects is the electrophoretic paint deposition method. In this process, the product is immersed in an aqueous bath of paint, which is the electrolyte. The product is the anode or cathode, and the tank wall or some auxiliary part is the other electrode in a DC circuit. During the application of voltage, the paint is plated onto the surface of the metal evenly and completely.